--- title: "Send data to the computer" subtitle: "micro:bit and the computer · Talk over USB · Lesson 1" --- # Send data to the computer **Name:** {{field-24}} **Date:** {{field-15}} **Class:** {{field-15}} > **Key question:** Weather stations, heart-rate monitors and the sensors in a science lab all do the same simple thing: send a reading, wait, send the next. A computer collects the readings and draws the graph. :::teacher-note **In one sentence:** Students make a micro:bit send sensor readings to the computer over USB as named lines of text, and watch them graphed. **Students should be able to say:** I can send a sensor reading to the computer again and again. I can explain what travels down the cable (a named line of text). I can send two values and choose how often they are sent. **Width:** the unmarked parts are the floor every student does (predict, run, investigate and make). Typical adds the modify practice; wider adds the real-world contexts. They add contexts, not difficulty. Students work in the online tutorial alongside this sheet. ::: ## Predict ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/b4960c33e4a3.png?v=fb3a9231a6407ea8) :::keep-together **This program runs on a micro:bit plugged into a computer. What arrives at the computer every half second?** ☐ A picture of the LEDs ☐ Just the number 128 ☐ A line of text, such as light:128 ☐ A graph My prediction, and why: {{lines-3}} ::: :::teacher-note **What happens:** A line of text: the name light, a colon, and the reading. The computer draws the graph from the lines; the micro:bit only sends text. ::: ## Run Run the program in the tutorial. Was your prediction right? What was different? {{lines-2}} :::typical ## Run Run the program in the tutorial. Was your prediction right? What was different? {{lines-2}} ::: ## Investigate ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/b4960c33e4a3.png?v=fb3a9231a6407ea8) :::keep-together ### Names **Why does each line start with a name (light:)?** ☐ To make the number bigger ☐ So the micro:bit remembers it ☐ The cable needs a name to work ☐ So the computer can tell different values apart when there are several ::: :::teacher-note **Answer:** So the computer can tell different values apart when there are several With light:128 and temperature:21 arriving on the same cable, the name says which is which. The graph draws one line per name. ::: :::keep-together ### No pause **You delete the pause. What happens?** ☐ One reading is sent, then it stops ☐ Nothing is sent ☐ The readings get more accurate ☐ Readings pour out as fast as the micro:bit can send them, far more than you need ::: :::teacher-note **Answer:** Readings pour out as fast as the micro:bit can send them, far more than you need Forever repeats as fast as it can. The pause sets how many readings a second you get: 500 ms is two a second. ::: :::keep-together ### Ben's logger Ben's program: ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/ca105b06a77d.png?v=9c7f73c9df351e18) **Ben's program sends one reading when the micro:bit starts, then nothing. Why?** ☐ Light level only works once ☐ The board can only read one line ☐ The cable is broken ☐ The block is in on start, not in forever, so it runs only once ::: :::teacher-note **Answer:** The block is in on start, not in forever, so it runs only once A logger has to read and send again and again: the send goes in forever, with a pause. ::: :::typical ## Modify **Two values.** Send the **temperature** too, with its own name. In Show data (or on the board), each name gets its own line. **Faster.** Make it send **ten readings a second**. Work in the tutorial. Plan first: what will you change, and how will you test it? {{box-4}} :::teacher-note **One possible solution.** Other correct programs are fine; check that the program runs and does what the task asks. **Two values:** ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/5262cf649412.png?v=4275f888f88ee62e) **Faster:** ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/02d65e58fd38.png?v=7f2858d085f2cf20) ::: ::: ## Make Make a **tilt logger**: send the micro:bit's **x** and **y** acceleration five times a second, and send the line **mark** when **A** is pressed, so you can mark a moment on the record. Tilt it in the simulator and watch Show data. Work in the tutorial. Plan first: what will you change, and how will you test it? {{box-4}} :::teacher-note **One possible solution.** Other correct programs are fine; check that the program runs and does what the task asks. ![The program as blocks](https://studio.learningwaypoints.com/tutorials/_pictures/makecode/code/6b76411a1e59.png?v=82d759b2a5969101) ::: ## Exit ticket :::keep-together **What does the computer receive when the micro:bit runs serial write value light, light level?** {{lines-3}} ::: :::teacher-note **Answer:** A line of text: the name light, a colon and the reading, such as light:128. :::